Cannulae are used in part during cardiopulmonary bypass to maintain circulation of blood through a patient's body. A cannula is inserted into the patient's venous system to drain blood, and the blood is then returned with the use of a cannula in combination with a heart-lung machine to the arterial system of the patient.
Cannulae are made in various sizes to match the patient size. These cannulae generally come in three forms: straight, straight with additional end holes (used primarily for extracorporeal membrane oxygenation (“ECMO”)), and right-angled. A right angle cannula is used primarily as a specific type of venous cannula to drain blood from the right side (or venous end) of the heart—that is, it allows cannulation of the vena cava.
Introduction of a venous cannula into a patient requires special surgical skill. In the usual situation, at least two surgeons/surgical assistants are needed to introduce the venous cannula into the patient due to the difficulty of inserting the cannula while making the necessary cut, placing the required sutures, and maintaining the opening. Moreover, the complexity of the introduction of the cannula is related to the size and the location of the vessel (i.e., the ease with which the vessel can be accessed, managed, and manipulated). In a fetal patient or premature newborn, the small vessels and small surgical and visual fields limit the feasibility of surgically using these cannulae. Similarly, in minimally invasive and robotic surgery, use of the traditional cannulae is made more challenging by the intrinsic distance from the surgical field as well as the limited access to the targeted area and indirect interaction with the vessel. Additionally, with all cannulations, the introduction of current cannulae into vessels oftentimes results in limited yet significant blood loss. To overcome these problems, and others, a new cannula is disclosed.